Safety is one of the key issues addressed during the design of an automobile and its components. For example, in the design of today's automobile, flexibility is typically a goal in the design of a seat. The vehicle must be able to carry passengers and cargo equally well.
One manner in which to alternately maximize seating for people and space for cargo is to provide for removable seats. While this may accomplish the goal of maximizing seat and cargo space, it adds complexity.
Another method includes seats which are movable between reclining positions (for passenger comfort), an upright position, and a cargo bearing position. In the cargo bearing position, the seat top is rotated relative to the seat bottom to provide a generally flat cargo bearing surface.
However, the seat reclining mechanism has to provide enough rigidity to protect the passenger during vehicle accidents.
An example of an early method of providing a seat reclining mechanism is shown in U.S. Pat. No. 3,788,698 issued to Norman W. Perkins on May 8, 1972. In the Perkins device, a fixed member having a plurality of saw-tooth shaped serrations is mounted to the bottom of the seat. The fixed member is movable between two positions. The frame of the top portion includes a rounded member having a plurality of saw-tooth shaped serrations. In a first position the serrations on the fixed member engage the serrations on the frame, thereby preventing movement of the seat back relative to the bottom. In a second position, the fixed member is pulled back from the frame, thereby disengaging the serrations. The seat back may thus be adjusted. However, the Perkins arrangement does not provide the required seat rigidity because only a small portion of the radius of the frame and fixed portion can be engaged at any one time.
Another example of a seat reclining mechanism found in the prior art is illustrated in U.S. Pat. No. 5,618,083 issued to Michael A. Martone and Tyrone R. Secord on Apr. 8, 1997. The Martone seat reclining device include a rack with a plurality of saw-toothed serrations and a fixed member with saw-toothed shaped serrations. A butterfly shaped arrangement transmits additional force from an external source to locking the rack and fixed portion in an engaged position.
However, this additional force is only applied when the force supplied by the external source is present, e.g., during a vehicle crash. If the additional force is not present, then the mechanism may become unintentionally unlocked, e.g., in the case of the vehicle hitting a bump in the road.
The present invention is aimed at overcoming one or more of the problems identified above.